Isolated Networks
Either acting as employees of companies or as individuals at home, today, people are used to relying on many communications means to access individuals or organizations useful in their professional or personal activities. This has been made possible thanks to two main achievements realized since the early stage of the Information Technology (IT) revolution: the existence and the compliance of worldwide standards, at different communication levels, like IP (Internet Protocol) or SMTP (Simple Messaging Transport Protocol), and the interconnection of different networks, the best example being the Internet network.
Unfortunately, under some specific conditions (or for some new business needs to address), it is not always possible to rely on an ubiquitous network to reach a given destination towards which a message must be delivered. The following examples illustrate this statement.
Recovery after Disaster
In the last decade, several disasters, like earthquakes, happened all over the world, resulting in thousands of victims and missing people. A critical problem faced by the rescue teams in such situations is the lack of communications in all the disaster areas, preventing an effective dispatch of medical or victim search staff. This lack of communications simply results from the disaster itself, either because the networking infrastructures have been destroyed, or because there is no electric power available to feed said networking infrastructures. This kind of situation is even worse when disasters occur in evolving countries. In these countries, the power or telecommunication infrastructures are usually less resilient than in evolved countries. Many times, the only available way to reach isolated areas is to rely on human communications, either motorized or not. A given message is passed from hand to hand before reaching its final destination. Because the exchange of information is of vital importance in such dramatic events, safe and efficient means are needed for carrying information between isolated points that can only be interconnected by means of conventional vehicles or rescuers.
Evolving Countries
Without speaking about disasters like earthquakes, several evolving countries are still without a nationwide telecommunication network infrastructure, unless they invest (if they can afford it . . . ) in satellite based networks. Even this may be a problem simply because the electric power infrastructure is also missing in some areas. As a result, such areas can rely only on conventional means, such as carrying digital information by vehicles or couriers, potentially with multiple hops, for passing a message to its final destination. As these countries have a legitimate need to get access to information, with all the social progress it drives, this kind of situation requires safe and efficient means for carrying information between isolated points.
Battlefield
On a battlefield, where at least two camps are involved, a given camp may occupy different positions without an existing communication infrastructure, although some conventional means allow goods to be exchanged between these positions (for instance using vehicles or soldiers). Furthermore, with the advance of tampering techniques, even if two positions are interconnected through communication means, it may be dangerous to use them since the enemy can capture strategic information exchanged between these two positions. Because the exchange of information is of strategic importance in modern conflicts, this kind of situation requires safe and efficient means for carrying information between isolated positions that only can be interconnected by means of vehicles of the army or soldiers.
Car Maintenance
Innovative breakthroughs in the automotive industry have resulted today in the pervasive use of electronics and embarked computers in vehicles. Nowadays, modern vehicles are able to detect and diagnose some deficiencies by themselves. However, they must report their findings to car manufacturer maintenance centers. By nature, vehicles are moving objects. However, they are not necessarily within range of such maintenance centers. Nevertheless, vehicles operate on roads or tracks, crossing other vehicles which afterwards may come within range of such access points, or which themselves may cross other vehicles which afterwards may come within range of such access points, and so on.
The reliability and the safety of modern vehicles is becoming a real concern, both for consumers and for manufacturers, this kind of situation requires safe and efficient means for carrying information from a given isolated vehicle to a maintenance center.
Limited Range Communication Means
Today, wireless technology allows information to be exchanged between low cost devices as long as they are within range. For instance, technologies like Bluetooth or RFID (Radio Frequency Identifier) have recently emerged, with very low cost devices. These techniques allow the exchange of information between devices operating with limited power requirements. Such devices can be easily embarked and powered on moving vehicles, as well as carried by people.
Problem
In each situation described previously, a problem is the exchange of a message from a point A to a point B, where both points are not interconnected, and where some “agents” are moving around. In the specification, this message will be referred to with the generic term “datagram”. The real difficulty is to take the best advantage of these moving agents, so that they can be used as a virtual networking infrastructure to carry this datagram from point A to point B.
International patent application WO 02/11346 (Goldberg et al.) from Motorola Inc. entitled “Method and Apparatus for transferring data” addresses this generic problem by treating a specific case related to the servicing of vending machines. More particularly, the invention disclosed in this patent application is directed to the transfer of data from a source device to a destination device by way of a courier whose primary function is not transporting such data. The invention relies on a single courier that first receives a datagram from the point A, then moves until he comes within range of point B, and finally transmits the datagram to point B. This patent relies on the assumption that the courier is sure that his movements will bring him from point A to point B. For the present problem as illustrated with the different examples previously introduced, this assumption is no longer valid, and therefore requires another solution.